The midseason finale, which will air on December 9, will see Brennan (Emily Deschanel) begin to identify with a murder victim.

When Brennan looks at the victim's photographs she sees herself and when she listens to recordings of the woman she hears herself.

"It's all told from Brennan's point of view," Nathan told Entertainment Weekly. "Brennan has the opportunity to see someone who mirrors her life so closely that she's forced to confront her own life the only way our Brennan could, which is as empirically impossible. She is forced to try to understand the complexities of life and emotion and emotional displacement, and she does. And that leads her to do something she never thought she would do in her relationship with Booth."

Nathan described the show as "our biggest emotional episode we've ever done with Booth and Brennan" and suggested that it will cause problems between Brennan and Hannah.

"There's something there that Hannah and Brennan have to contend with," he teased.